This invention is related to a semiconductor light emitting device integrated with a Si-heat sink which contains not only a beam deflector but also the driving integrated circuits. A semiconductor light emitting device comprising a Si-substrate 2, V-groove 3 etched into substrate 2 and a beam deflector 9 on the wall of V-groove 3 wherein the transistor 22 for the driving and control on said Si-substrate is integrated so that light emitting device 1 and said integrated circuit are integrally mounted. The advantage of this invention is that the integration of the driving transistor with the light emitting device in the same package head reduces the packaging and bonding problems. Obtained is a compact optical system which easily radiates the heat dissipated by devices. This is in contrast to conventional light emitting devices which use the Si-substrate only as a mount and beam deflector.